Sharpening device for a cloth cutting machine



SHARPENING DEVICE FOR A CLOTH CUTTING MACHINE Filed Aug. 12, 1963 R. STUCKER Feb. 8, 1966 3 Sheets-Sheet 1 Feb. 8, 1966 R. STUCKER 3,233,371

SHARPENING DEVICE FOR A CLOTH CUTTING MACHINE Filed Aug. 12, 1963 3 Sheets-Sheet 2 w I mm i A I r I Feb. 8, 1966 R. STUCKER 3,233,371

SHARPENING DEVICE FOR A CLOTH CUTTING MACHINE Filed Aug. 12, 1965 3 Sheets-Sheet 5 United States Patent ()fifice 3,233,371 Patented Feb. 8, 1966 3,371 SHARPENING IIEVIQE FOR A LOTH CUTTING MAQ Robert Stucker, Cincinnati, (llhio, assignor to The Wolf Machine Company, Cincinnati, Ohio, a corporation of Ohio Filed Aug. 12, 1963, Ser. No. 301,525 9 Claims. (Cl. 51-249) This invention relates to a cloth cutting machine having a reciprocating knife blade and, more particularly, to a device for sharpening the knife blade of the cloth cutting machine while the knife blade is reciprocating.

Various types of devices have been employed for sharpening the reciprocating knife blade of a cloth cutting machine. Some of these sharpening devices have employed fixed grinding wheels, which only rotate due to contact with the knife blade; these create burrs on the knife blade whereby the cloth is damaged. Other sharpening devices, such as the apparatus disclosed in US. Patent 2,730,850 to Rockwood et al., have simultaneously maintained rotating wheels on opposite sides of the knife in contact with the knife. However, the aforesaid Rockwood et al. patent requires the grinding wheels to be set at a specific angle along with additional mechanism to provide for wear due to the specific angle requirement in order to produce the desired sharpening effect. Furthermore, the simultaneous sharpening of both blades produces increased stresses on the blade.

The present invention satisfactorily solves these problems by providing a sharpening device that sharpens only one side of the reciprocating knife blade of a cloth cutting machine at a time with a rotating grinding wheel. Thus, there is no need to set the wheels at a specific angle as the rotating wheel may move parallel to the side of the knife. Additionally, only one side of the knife is engaged during the sharpening operation to reduce stresses in the knife from the sharpening structure.

Still other sharpening devices have employed driven rotating grinding wheels for sharpening both sides of the knife at the same time. However, these devices have utilized the curved surface of the grinding wheel for sharpening and, accordingly, decreased the amount of contact between the grinding wheel and the knife. By sharpening only one side of the knife at a time, the pres ent invention is able to employ the flat surface of the grinding wheel and obtain contact with a greater area of the knife to produce the desired sharpening effect.

The attached drawings illustrate a preferred embodiment of the invention, in which:

FIGURE 1 is a perspective view of a cloth cutting machine including the present invention;

FIGURE 2 is an enlarged perspective view of a portion of the structure of FIGURE 1 with the sharpening device adjacent its lowermost position;

FIGURE 3 is a sectional view of the sharpening device and its driving mechanism with the sharpening device in FIGURE 8 is a sectional view taken on the line 8-8 of FIGURE 5.

Referring to the drawings and particularly FIGURE 1, there is shown a cloth cutting machine 1 having a base 2 with rollers 3 therein to permit free movement of the cloth cutting machine on a table supporting the cloth to be cut. A vertical standard or support 4 extends upwardly from the base and has a housing 5 supported thereon. The housing 5 has an electric motor and a knife reciprocating mechanism disposed therein.

A removable unit or housing 6, which contains a sharpening drive mechanism, is secured to the housing 5. A handle 7 is attached to the lower portion of the housing 5 for guiding the cloth cutting machine 1. A toggle switch 8 is mounted adjacent the bottom of the housing 5 to control the electric motor.

A knife 9 is supported within guideways in the vertical standard 4 for reciprocating movement therein. A presser foot 1%, which bears against the top of the cloth being cut, is carried by a vertical guard 11. The upper end of the vertical guard 11 terminates in a handle 12, which slides within a slot 13 in the housing 6 to provide vertical adjustment of the presser foot 10. The presser foot 10 is held in any vertical position by spring biased means (not shown) within the housing 6 engaging against the vertical guard 11 as described in the aforesaid Rockwood et al. patent.

The knife 9 is driven in its reciprocating motion within the vertical standard 4 by the motor within the housing 5. The structure for reciprocating the knife 9 is preferably that shown and described in the aforesaid Rockwood et al. patent.

As shown in FIGURE 3, the exterior surface of a reversing drive shaft 14 has an endless peripheral square thread 15 cut therein so that there is a section extending downwardly which connects with the section extending upwardly which in turn connects with the downwardly extending section. The reversing drive shaft 14 is driven by the electric motor, which drives the knife 9, through suitable mechanism such as shown and described in the aforesaid Rockwood et al. patent. However, the reversing drive shaft 14 is driven only when a starting lever is actuated. The lever cannot be actuated to allow the reversing drive shaft 14 to be driven until the presser foot it) is resting on the base 2 as shown and described in the aforesaid Rockwood et al. patent.

A sharpener tube 16 surrounds the reversing drive shaft 14 and is concentric therewith. The interior of the reversing drive shaft 14 is hollow and is non-circular in shape, preferably square. A non-circular grinding wheel drive shaft 17 of the same shape as the interior of the shaft 14 is disposed within the interior of the shaft 14 and concentric therewith.

The sharpener tube 16 has a spring-biased follower (not shown), which engages the endless peripheral thread 15 on the reversing drive shaft 14, secured thereto as shown and described in the aforesaid Rockwood et al. patent. The tube 16 and its follower are prevented from rotation by suitable means as shown and described in the aforesaid Rockwood et al. patent. Thus, rotation of the reversing drive shaft 14 causes the sharpener tube 16 to move in a vertical reciprocating motion so that its follower will travel to the bottom of the thread 15 and then reverse its direction and travel upwardly to the top of the thread in the well-known manner. Of course, the reversing drive shaft 14 is automatically disconnected from the electric motor after the sharpener tube 16 has completed one downward and upward movement as shown and described in the aforesaid Rockwood et al. patent. If further sharpening is desired, the starting lever 3 must be actuated as shown and described in the aforesaid Rockwood et al. patent.

The sharpener tube 16 supports a carriage 18, which includes an upper portion 19 and a lower portion 20. As shown in FIGURE 5, grinding wheels 21 and 22, which are adapted to sharpen the knife 9 by having flat surfaces engage the knife, are supported on the lower portion of the carriage 18.

The non-circular shaft 17 terminates in a circular shaft 23, which is supported by a ball bearing 24 within the interior of the sharpener tube 16. The bearing 24 is positioned between an annular shoulder 25 and a snap ring 26, which is disposed within a groove in the inner wall of the sharpening tube 16. The shaft 17 is secured to an annular member 27, which carries a driving gear 28, through a pin 29 engaging the circular shaft 23.

The driving gear 28 meshes with an idler gear 30 (see FIGURE 4), which is mounted on a shaft 31. The shaft 31 is supported in bearings 32 and 33 within the upper portion 19 of the carriage 18.

The idler gear 31) meshes with a driven gear 34, which is supported on an annular member 35. The annular member 35 is connected to a shaft 36 by a pin 37. The upper end of the shaft 36 is supported in the upper portion 19 of the carriage 18 by a bearing 84, which is supported on the annular member 35 by an annular spacer 85.

The lower end of the shaft 36 has a pulley 38 threadedly secured thereto. The upper end of the pulley 38 abuts against the lower end of a bearing 39, which along with a bearing 41) rotatably supports the shaft 36 within the lower portion 28 of the carriage 18.

A pulley 41 is rotatably mounted on the shaft 36 by a bearing 42. The pulley 41 is spaced from the lower portion 20 of the carriage 18 by an annular spacer 43, which is disposed between the upper surface of the bearing 40 and the lower surface of the bearing 42. The pulley 41 is spaced from the lower surface of the upper portion 19 of the carriage 18 by an annular spacer 44, which bears against the upper surface of the bearing 42 and the lower surface of a bearing 45. The bearing 45 rotatably mounts the shaft 36 in the lower part of the upper portion 19;.

A snap ring 46 is disposed in a groove within the upper portion 19 of the carriage 18 and engages the upper surface of the bearing 45 to limit upward movement of the shaft 36 and its associated parts. A similar snap ring 47 is disposed in a groove within the lower portion 20 of the carriage 18 to limit downward movement of the same structure.

Accordingly, any downward motion of the sharpener tube 16 moves the carriage 18 downwardly. Downward movement of the carriage 18 causes the shaft 17 to move downwardly. However, the reversing drive shaft 14, which always rotates in the same direction, imparts rotation to the shaft 17 whereby the pulley 38 is driven through the gears 28, 39, and 34 and the shaft 36.

The lower portion 20" of the carriage 18 has a pair of passages 48 and 49 extending therethrough (see FIGURE 5). A rod 50, which has a bifurcated bracket 51 at its end formed integral therewith, is disposed within the passage 48. A rod 52, which has a bifurcated bracket 53 formed integral therewith on one end, is disposed within the passage 49.

The rod 58 has a flat 54 in its surface for cooperation with a screw 55 in the lower portion 2%) of the carriage 18 to prevent twisting of the rod about its axis. However, rod 50 is free to slide longitudinally withinlimits as will be seen. The rod 52 also has a fiat 56 in its surface for cooperation with a screw 57 in the lower portion 20 of the carriage 18 to prevent twisting of the rod 52 about its axis.

Each grinding wheel 21 and 22 is carried by a bearing assembly 5858. The two bearing assemblies are identical and their construction is best fllustrated in the cross 4 sectional view of FIGURE 8. As shown, each grinding wheel has a shaft 59 projecting axially from one side thereof. This shaft is splined as shown at 59a and these splines key the shaft to a pulleywheel 68 which is approximately centered on the shaft between the outer end thereof and-the grinding wheel. Apair of cylindrical bushings 61-61 journal shaft 59, being disposed one on either side of pulley wheel 68. The parts are locked onto shaft 59 by a snap ring 63. Each bushing has two parallel chordal slots 62-62 therein adjacent pulley wheel 68 to receive the arms of the respective bifurcated brackets 51 53 such that the complete bearing assemblies may be slipped into place within the brackets 51-53 for support thereby. This arrangement of the grinding wheels 21 and 22 insures that flat surfaces of-the grinding wheels Contact the appropriate portion of the knife 9 to sharpen it.

The shafts 59-459 are held within the bifurcated ends of brackets 51 and 53, respectively, by a continuous belt 64. The belt passes around the drive pulley 38, then around the pulley 68 at the left, then pulley at the right, and then around idler pulley 41. Thus, the belt 64 serves a dual function of holding the bearing assem blies 58 in the bifurcated brackets 51 and 53, respectively, and providing the drive power for the grinding wheels 21 and 22.

Resilient means, such as a spring 65, surrounds the rod 58 and is disposed between the bifurcated bracket 51 and a recess 66 in the lower portion 28 of the carriage 18 to provide tension to the belt 64. A set screw 67 is threaded within the passage 48 for abutting engagement with the end of the rod 52 to provide proper positioning of the rods 58 and 52. Thus, the set screw 67 cooperates with the belt 64 and the spring to position the grinding wheels 21 and 22.

In order to oscillate the Wheels 21 and 22 so that first one and then the other contacts opposite sides of the knife 9, the lower part 28 of the carriage 18 is moved with respect to the upper part 19. The oscillating structure includes a bell crank lever 68, which is pivotally connected by a screw 69 to the upper part 19 of the carriage 18. A depending arm 78 of the bell crank lever 68 has a slot 71 therein for reception of a pin or stud 72, which is secured to the lower part 20 of the carriage 18. Of course, the slot 71 could be formed in the lower portion 20 and the pin or stud 72 mounted on the arm 7 0 if desired.

A vertically disposed reach rod 73 has its lower, hooked end passing through a bore in an arm 74 of the bell crank lever 68 to provide a pivotal connection therebetween. A hair spring 75 is attached to the terminal end of the rod 73 to counteract the torque created by the rotation of the belt 64 in driving the grinding wheels 21 and 22. The other end of the spring 75 is secured to the upper part 19 of the carriage 18 by a screw 76 and a spacer 77 (see FIGURES 2 and 4).

The upper end of the rod 73 (see FIGURE 6) extends through a friction member in the housing 6. The friction member includes a pair of friction pads 7878, which preferably are made of a plastic material such as nylon. These pads are disposed on opposite sides of reach rod 73 within a cylindrical receptacle 79 through which rod 73 passes diametrically as shown. The receptacle 79 has a screw threaded end to threadedly receive a member 80, which has a recess with a spring 81 disposed therein. The force of the spring 81 is determined by the advancement of the member 80 along the threads on the receptacle 79, and this, in turn, determines the frictional resistanoe placed upon reach rod 73 by pads 78-78.

When initially centering the grinding wheels 21 and 22 with respect to the knife 9, the friction spring 81 is loosened by unthreading the member 80 from the receptacle 79. This frees reach rod 73 so that the torque of the running belt upon the lower part 20 of the carriage 18 is the only appreciable force acting upon said lower part. The hair spring 75 is then wound or unwound by ma- 5. nipulating the screw 76 until the knife 9 is centered between the wheels 21 and 22. This is done while the grinding wheels are being driven and the carriage is moving up and down. As previously mentioned, the hair spring 75 counteracts the torque of the belt 64 so that the absence of the hair spring 75 would result in the rotation of the belt 64 causing only one of the Wheels 21 and 22 to contact the knife 9. After the grinding Wheels 21 and 22 are centered properly, the friction spring 81 is tightened by advancing the member 80 into the receptacle 79. Thereafter, with torque counterbalanced, the friction forces upon reach rod 73 is fully effective in both the upward and downward movements of the carriage, as will now be explained. v V

The friction member causes the lower portion 20 of the carriage 18 to oscillate with respect to the upper portion 19. With the device in the position of FIGURE 7, the carriage 18 is ready to start its downward movement. As the carriage 18 starts downwardly, downward movement of the rod 73 is momentarily prevented or delayed by engagement of the rod 73 within the friction pad 78. As a result, the arm 74 is held stationary to cause clockwise rotation of the belt crank lever 68 from the centered position of FIGURE 7 to the position shown in solid lines in FIGURE 6. V This results in the lower portion 20 of the carriage 18 rotating about the shaft 36 as a pivot point to move the grinding wheel 22 away from contact with one side of the knife 9 and to move the grinding wheel 21 into contact with the other side of the knife 9. (See FIGURE 5.) This movement of the lower portion 20 of the carriage 18 about the shaft 36 as the pivot point is due to the cooperation between the slot 71 in the arm 70 of the lever 68 and the pin or stud 72 on the lower portion 20 of the carriage 18.

When the carriage 18 reaches the end of its downward travel and starts back up, the relation of the first portion 19, the second portion 20, the lever 68, and the rod 73 will be as shown by dot-dash lines in FIGURE 6. This is because the initial upward movement of the carriage 18 results in upward movement of the rod 73 being momentarily delayed by the friction pad 78. Accordingly, the bell crank lever 68 rotates counter-clockwise (as viewed in FIGURE 6). As soon as the slight amount of rotation of the lever 68 has occurred, the rod 73 then advances through the friction pad 78. Theslot 71 in the arm 70 of the lever 68 and the pin 72 on the lower portion 20 of the carriage 18 cooperate to cause rotation of the lower portion 20 about the shaft 36 as its pivot point to move the grinding wheel 22 into contact with the one side of the knife 9 while the grinding wheel 21 is moved away from contact with the other side of the knife 9.

The lever 68 has a third arm 82 with a centering slot 83 therein. This centering slot cooperates with a pin 86 that projects horizontally outwardly from the housing of the machine in position to engage a cam surface 87 at the upper end of the bellcrank lever and to the right '(as shown in FIGURE 6) of slot 93. This contact occurs at the upper end of the travel of carriage 18 only, and it shifts thecarn'age into the centered position illustrated in FIGURE 7 just as the drive to the two grinding wheels is disconnected automatically as occurs at the end of each upward pass of carriage 18. Therefore, the grinding Wheels are held such that neither one is in contact with 'the knife blade during the normal cloth cuttingoperations.

Considering the operation of the present invention with the switch 8 actuated to energize the motor, the knife 9 reciprocates. As described in the aforesaid Rockwood et al. patent, movement of the presser foot 10 into engagement with the base 2 by the operator allows the starting lever to be actuated to start rotation of the reversing drive shaft 14 to move the sharpener tube 16 downwardly. This causes downward movement of the carriage 18.

However, when the carriage 18 starts its downward movement, the rod 73 is momentarily prevented from moving downwardly due to its engagement with the friction pad 78. As a result, the lever 68 rotates into the position shown in solid lines in FIGURE 6 from the centered position of FIGURE 7. p This clockwise motion of the lever 68 results in the lower portion 20 of the carriage 18 pivoting about the shaft 36 as a center to move the grinding wheel 21 into contact with its side of knife 9. This arrangement of the grinding wheels 21 and 22 with respect to the knife 9 is shown in FIGURE 5. Thus, as the carriage 18 moves downwardly, the spinning grinding wheel 21 moves downwardly to sharpen the side of the knife on which the grinding wheel 21 is located.

The downward movement of the sharpener tube 16 not only moves the carriage 18 downwardly, but it also moves the non-circular shaft 17 downwardly. However, the noncircular shaft 17 also rotates due to the rotation of the reversing drive shaft 14 so that the pulley '38 and the belt 64 are driven to rotate the grinding wheels 21 and 22. It should be understood that the grinding wheels 21 and 22 are always driven in the same directions irrespective of the position of the carriage 18, but due to the arrangement of the belt 64, the direction of rotation of one wheel is opposite that of the other.

When the carriage 18 reaches the bottom of its downward travel, the thread 15 cooperates with the follower on the sharpener tube 16 to reverse the direction of the tube 16 and the carriage 18 starts to move upwardly. Because the rod 73 is momentarily delayed in its upward movement due to its contact with the friction pad 78 when the upward movement of the carriage 18 starts, the lever 68 rotates from the position shown in solid lines in FIG- URE 6 to the position shown in dot-dash lines in this figure. This counter-clockwise motion of the lever 68 results in the lower portion 20 of the carriage 18 rotating about the shaft 36 as a center point to move the grinding wheel 22 into contact with the side of the knife 9 on which the grinding wheel 22 is disposed while removing the grinding wheel 21 from engagement with the other side of the knife 9. Since the shaft 14 always rotates in the same direction, the rotation of the drive belt 64 is always in the same direction.

When the carriage 18 reaches its uppermost position, the pin 86 engages slot 83 to center the carriage and the reversing drive shaft 14 is automatically disconnected from the motor as shown and described in the aforesaid Rockwood et al. patent. If a furthersharpening of the knife 9 is desired, the starting lever must again be actuated. Otherwise, the presser foot 10 is raised to permit the cloth, which is to be cut, to be inserted thereb-eneath.

Whenever it is desired to remove either of the grinding wheels 21 and 22, this is quickly accomplished by exerting force against the spring to move the rod 5!) inwardly within the passage 48 to release the belt 64. With the belt 64 released, either of the grinding wheels 21 and '22 may be easily removed from the support of its bifurcated bracket 51 or 53, respectively.

An advantage of this invention is that the grinding wheels move parallel only to the knife to sharpen it, which movement, it is found, reduces 'burring of the blade to an absolute minimum. Another advantage is that each side of the knife is sharpened separately to provide a uniform cutting edge along the entire side.

For purposes of exemplification, a particular embodiment of the invention has been shown and described according to the best present understanding thereof. However, it will be apparent that changes and modifications in the arrangement and construction of the parts thereof may be resorted to without departing from the true spirit and scope of the invention.

Having described my invention, I claim:

1. In a cloth cutting machine having a vertically reciprocating knife for cutting cloth, the improvement comprising a carriage having spaced first and second portions, grinding means mounted on said second portion of said carriage for contacting opposite sides of said knife to sharpen the opposite sides of said knife, means to move said carriage in a vertically reciprocating motion while said knife is reciprocating, means to rotate said grinding means whenever said carriage is reciprocating, a movable member pivotally connected to said first portion of said carriage, said movable member being connected to said second portion of said carriage through a pin and slot connection, aid movable member having an arm extending therefrom, a rod pivotally connected to said arm, resilient means attached to the carriage and to the end of the rod adjacent said arm, and a fixed friction member on said cloth cutting machine, said rod extending into said fixed friction member whereby when said carriage moves downw'ardly said rod is momentarily prevented by said fixed friction member from moving downwardly to rotate said movable member to move said second portion of said carriage so that said grinding means on one side of said knife is moved into contact with said one side of said knife and the grinding means on the other side of said knife is moved away from contact with said other side of said knife and when said carriage moves upwardly said rod is momentarily prevented by said fixed friction member from moving upwardly to rotate said movable member to move said second portion of said carriage so that said grinding means on said other side of said knife is moved into contact with said other side of aid knife and said grinding means on said one side of said knife is moved away from contact with said one side of said knife.

2. In a cloth cutting machine having a vertically reciprocating knife for cutting cloth, the improvement comprising a carriage having spaced first and second portions, means to move said carriage in a vertically reciprocating motion while said knife is reciprocating, a pair of grinding wheels mounted on said second portion of said carriage and spaced from each other for contacting opposite sides of said knife to sharpen the opposite sides of said knife, a drive belt connecting said grinding wheels, means to actuate said drive belt to rotate said grinding wheels whenever said carriage is reciprocating, a movable member pivotally connected to said first portion of said carriage, said movable member being connected to said second portion of said carriage through a pin and slot connection, said movable member having an arm extending therefrom, a rod pivotally connected to said arm, resilient means attached to the carriage and to the end of the rod adjacent said arm, and a fixed friction member on said cloth cutting machine, said rod extending into said fixed friction member whereby when said carriage moves downwardly said rod is momentarily prevented by said fixed friction member from moving downwardly to rotate said movable member to move said second portion of said carriage so that said grinding wheel on one side of said knife is moved into contact with said one side of said knife and said grinding wheel on the other side of said knife is moved away from contact with said other side of said knife and when said carriage moves upwardly said'rod is momentarily prevented by said fixed friction member from moving upwardly to rotate said movable member to move said second IPOI'tiOIl of said carriage so that said grinding wheel on said other side of said knife is moved into contact with said other side of said knife and said grinding wheel on said one side of said knife is moved away from contact with said one side of said knife.

3. In a cloth cutting machine having a vertically reciprocating knife for cutting cloth, the improvement comprising a carriage having spaced first and second portions, a pair of grinding wheels mounted on said second portion of said carriage and spaced from each other for contacting opposite sides of said knife to sharpen the opposite sides of said knife, a drive belt connecting said grinding wheels, a reversing-drive shaft to move said carriage in a vertically reciprocating direction while said knife is reciprocating, a non-circular shaft disposed within said reversing drive shaft and rotated thereby, said noncircular shaft being adapted to actuate said drive belt, a movable member pivotally connected to said first portion of said carriage, means connecting said movable memher to said second portion of said carriage to allow relative movement of said second portion with respect to said first portion when said movable member is actuated, and means to move said movable member when said carriage changes direction, the last named means rotating said movable member to move said second portion of said carriage with respect to said first portion to move one of said grinding wheels into contact with one side of said knife while simultaneously moving the other of said grinding wheels out of contact With the opposite side of said knife whenever the carriage changes direction.

4. In a cloth cutting machine having a vertically reciprocating knife for cutting cloth, the improvement comprising a cariage having spaced first and second portions, a pair of grinding wheels mounted on said second portion of said carriage and spaced from each other for contacting opposite sides of said knife to sharpen the opposite sides of said kiife, a drive belt connecting said grinding wheels, a reversing drive shaft to move said carriage in a vertically reciprocating direction while said knife is reciprocating, a non-circular shaft disposed within said reversing drive shaft and rotated thereby, said non-circular shaft being adapted to actuate said drive belt, a movable member pivotally connected to said first portion of said carriage, said movable member being connected to said second portion of said carriage through a pin and slot connection, and means pivotally connected to said movable member to momentarily delay the movement of a portion of said movable member when said carriage changes direction, said delay means rotating said movable member to move said second portion of said carirage with respect to said first portion to move one of said grinding wheels into contact with one side of said knife while moving the other of said grinding wheels out of contact with said knife whenever the carriage changes direction.

5. In a cloth cutting machine having a vertically reciprocating knife for cutting cloth, the improvement comprisign a carriage having spaced first and second portions, a pair of grinding wheels mounted on said second portion of said carriage and spaced from each other for contacting opposite sides of said knife to sharpen the opposite sides of said-knife, a drive belt connecting said grinding wheels, a reversing drive shaft to move said carriage in a vertically reciprocating direction while said knife is reciprocating, a non-circular shaft disposed within said reversing driving shaft and rotated thereby, said noncircular shaft being adapted to actuate said drive belt, a movable member pivotally connected to said first portion of said carriage, said movable member being connected to said second portion of said carriage through a pin and slot connection, said movable member having an arm extending therefrom, a rod pivotally connected to said arm, resilient means attached to the carriage and to the end of the rod adjacent said arm, and a fixed friction member on said cloth cutting machine, said rod extending into said fixed friction member whereby when said carriage moves downwardly said rod is momentarily prevented by said fixed friction member from moving downwardly to rotate said movable member to move said second portion of said carriage so that said grinding wheel on one side of said knife is moved into contact with said one side of said knife and the grinding wheel on the other side of said knife is moved away from conntact with said other side of said knife and when said carraige moves upwardly said rod is momentarily prevented by said fixed friction member from moving upwardly to rotate said movable member to move said second portion of said carriage so that said grinding wheel on said other side of said knife is moved into contact with said other side of said knife and said grinding wheel on said one side of said knife is moved away from contact with said one side of said knife.

6. In a cloth cutting machine having a vertically reciprocating knife for cutting cloth, the improvement comprising a support, a pair of rods exending therefrom, means to retain each of said rods against rotation about its axis, each of said rods having a bifurcated bracket at its outermost end, a pair of shafts, each of said shafts having a grinding wheel mounted thereon to sharped opposite sides of the knife, means associated with each of said shafts having spaced slots therein for receiving the ends of one of said brackets to form a unitary connection therebetween, a pulley secured to each of said shafts between said spaced slots, a continuous belt passing over said pulleys on said shafts and connected to a driving means, resilient means to maintain said belt under tension, and means acting against the end of one of the rods remote from its bracket to adjust the relative position of said grinding wheels with respect to each other.

7. In a cloth cutting machine having a vertically reciprocating knife for cutting cloth, the improvement comprising a support, a pair of rods extending thereform, means to retain each of said rods against rotation about is axis, each of said rods having a bifurcaed bracket at its outermost end, a pair of shafts, each of said shafts having a grinding wheel mounted thereon to sharpen opposite sides of the knife, means associated with each of said shafts spaced slots therein for receiving the ends of one of said brackets to form a unitary connection therebetween, a pulley secured to each of said shafts between said spaced slots, a continuous belt passing over said pulleys on said shafts and connected to a driving means, resilient means surrounding one of said rods between the bracket and the support to maintain said belt under tension, and means acting against the end of the rod remote from the bracket to adjust the relative position of said grinding wheels with respect to each other.

8. In a cloth cutting machine having a vertically reciprocating knife for cutting cloth, the improvement comprising a support, a pair of rods extending therefrom, means to retain each of said rods against rotation about its axis, each of said rods having a bifurcated bracket at its outermost end, a pair of shafts, each of said shafts having a grinding wheel mounted thereon to sharpen opposite sides of the knife, means associated with each of said shafts having spaced slots therein for receiving the ends of one of said brackets to form a unitary connection therebetween, a pulley secured to each of said shafts between said spaced slots, a continuous belt passing over said pulleys on said shafts and connected to a driving means, a spring surrounding one of said rods between the bracket and the support to maintain said belt under tension, and an adjusable set screw acting against the end of the rod remote from the bracket to adjust the relative position of said grinding wheels with respect to each other.

9. In a cloth cutting machine having a vertically reciprocating knife for cutting cloth, the improvement comprising a carrai-ge, means to move said carriage in a vertically reciprocating movement, a pair of rods extending from the carriage, means to retain each of said rods against rotation about its axis, each of said rods having a bifurcated bracket at its outermost end, a pair of shafts, each of said shafts having a grinding wheel mounted thereon to sharpen opposite sides of the knife, means associated with each of said shafts having spaced slots therein for receiving the ends of one of said brackets to form a unitary connection therebetween, a pulley secured to each of said shafts between said spaced slots, a continuous belt passing over said pulleys on said shafts, resilient means to maintain said belt under tension, means to drive said belt to rotate said grinding wheels when said carriage is reciprocating, means to oscillate said carriage to maintain only one of said wheels in contact with said knife when said carriage moves in one direction to sharpen one side of said knife and to maintain only the other of said grinding wheels in contact with said knife when said carriage moves in the opposite direction to sharpen the other side of said knife, and means acting against the end of one of the rods remote from its bracket to adjust the relative position of said grinding wheels with respect to each other.

References Cited by the Examiner UNITED STATES PATENTS 1,050,891 1/1913 Wildman et al. 30139 2,171,604 9/ 1939 Segal 51249 2,290,015 7/ 1942 Blesch 51-249 2,5 29,441 11/ 0 Zawistowski 51249 2,730,850 1/ 1956 Rockwood et al 51249 ROBERT C. RIORDON, Primary Examiner.

LESTER M. SWINGLE, Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,233,371 February 8, 1966 Robert Stucker It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 8, line 19, for "kiife" read knife line 32, for "carirage" read carriage lines 38 and 39, for "comprisign" read comprising same column 8, line 63, for "conntact" read contact column 9, line 20, for "is" read its same line 20, for "bifurcaed" read bifurcated same column 9, line 24, after "shafts" insert having Signed and sealed this 10th day of January 1967 (SEAL) Amt:

ERNEST W. SWIDER Attesting Officcr 

1. IN A CLOTH CUTTING MACHINE HAVING A VERTICALLY RECIPROCATING KNIFE FOR CUTTING CLOTH, THE IMPROVEMENT COMPRISING A CARRIAGE HAVING A SPACED FIRST AND SECOND PORTIONS, GRINDING MEANS MOUNTED ON SAID SECOND PORTION OF SAID CARRIAGE FOR CONTACTING OPPOSITE SIDES OF SAID KNIFE TO SHARPEN THE OPPOSITE SIDES OF SAID KNIFE, MEANS TO MOVE SAID CARRIAGE IN A VERTICALLY RECIPROCATING MOTION WHILE SAID KNIFE IS RECIPROCATING, MEANS TO ROTATE SAID GRINDING MEANS WHENEVER SAID CARRIAGE IS RECIPROCATING, A MOVABLE MEMBER PIVOTALLY CONNECTED TO SAID FIRST PORTION OF SAID CARRIAGE, SAID MOVABLE MEMBER BEING CONNECTED TO SAID SECOND PORTION OF SAID CARRIAGE THROUGH A PIN AND SLOT CONNECTION, SAID MOVABLE MEMBER HAVING AN ARM EXTENDING THEREFROM, A ROD PIVOTALLY CONNECTED TO SAID ARM, RESILIENT MEANS ATTACHED TO THE CARRIAGE AND TO THE END OF THE ROD ADJACENT SAID ARM, AND A FIXED FRICTION MEMBER ON SAID CLOTH CUTTING MACHINE, SAID ROD EXTENDING INTO SAID FIXED FRICTION MEMBER WHEREBY WHEN SAID CARRIAGE MOVES DOWNWARDLY SAID ROD IS MOMENTARILY PREVENTED BY SAID FIXED FRICTION MEMBER FROM MOVING DOWNWARDLY TO ROTATE SAID MOVABLE MEMBER TO MOVE SAID SECOND PORTION OF SAID CARRIAGE SO THAT SAID GRINDING MEANS ON ONE SIDE OF SAID KNIFE IS MOVED INTO CONTACT WITH SAID ONE SIDE OF SAID KNIFE AND THE GRINDING MEANS ON THE OTHER SIDE OF SAID KNIFE IS MOVED AWAY FROM CONTACT WITH SAID OTHER SIDE OF SAID KNIFE AND WHEN SAID CARRIAGE MOVES UPWARDLY SAID ROD IS MOMENTARILY PREVENTED BY SAID FIXED FRICTION MEMBER FROM MOVING UPWARDLY TO ROTATE SAID MOVEABLE MEMBER TO MOVE AND SECOND PORTION OF SAID CARRIAGE SO THAT SAID GRINDING MEANS ON SAID OTHER SIDE OF SAID KNIFE IS MOVED INTO CONTACT WITH SAID OTHER SIDE OF SAID KNIFE AND SAID GRINDING MEANS ON SAID ONE SIDE OF SAID KNIFE IS MOVED AWAY FROM CONTACT WITH SAID ONE SIDE OF SAID KNIFE. 